package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import cn.hutool.core.util.BooleanUtil;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.TimeUnit;

public class SimpleRedisLock implements ILock{
//    锁的key值
    private String name;
    private StringRedisTemplate stringRedisTemplate;
//    key值前缀
    private static final String KEY_PREFIX = "lock:";
//    val值前缀
    private static final String ID_PREFIX = UUID.randomUUID().toString(true)+"-";
//   lua脚本
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }
    public SimpleRedisLock(String name, StringRedisTemplate stringRedisTemplate) {
        this.name = name;
        this.stringRedisTemplate = stringRedisTemplate;
    }

    @Override
    public boolean tryLock(long timeoutSec) {
//        获取当前线程id
        String threadId = ID_PREFIX+Thread.currentThread().getId();
        Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX+name,threadId+"",timeoutSec, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(success);
    }

    @Override
    public void unLock() {
//        调用lua脚本
        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX+name),
                ID_PREFIX+Thread.currentThread().getId()
        );
    }
//      判断+释放不是原子性操作，仍会导致误删
//    @Override
//    public void unLock() {
////        获取线程标识
//        String threadId = ID_PREFIX + Thread.currentThread().getId();
//        String val = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
//        if(threadId.equals(val)){
//            stringRedisTemplate.delete(KEY_PREFIX+name);
//        }
//    }

}
